Fancy losing weight, looking younger, living longer, fending off Alzheimer’s, Parkinson’s and even cancer, whilst eating whatever you want? This is only some of what the 5:2 fasting diet claims to offer, and the only catch is that you have to fast twice a week. The ‘fast’ days do not require complete starvation, but instead involve heavily restricted calories – 500 for a woman and 600 for a man. It’s up to the individual how to make up the calories, but the suggestion is that you eat breakfast and one other meal, either lunch or dinner.

The evidence is strong that it’s a very effective way to lose weight. But there’s more to it than that – much has been made of the link between this pattern of eating and increased longevity. Research conducted by the Baltimore National Institute on Aging indicates that levels of the hormone insulin-like growth factor 1 (IGF-1) are lowered by twice-weekly fasting. Controlling levels of IGF-1 can promote longevity as well as offering protection against a range of diseases.

High levels of IGF-1 are thought to increase the cell divisions associated with cancer, hence the possibility that reducing it may offer defence against it. Although this evidence is encouraging, the sceptical scientific community still feel that more extensive research needs to be conducted before conclusions can be drawn. Some critics have suggested that the extremes involved might result in the development of eating disorder, although there is no hard evidence for this either.

Could it be that eating hardly anything twice a week is doable because of the fact that, for the rest of the time, one is at liberty to enjoy whatever one fancies, be it cake, steak, or booze?

Since the BBC broadcast a documentary about it last year, the diet has grown hugely in popularity, with celebrity support coming from the likes of Hugh Fearnley-Whittingstall. Is there something different about this approach to reducing the amount we eat, or is it just another boom and bust fad diet like Atkins or Dukan? According to those who champion it, this approach to reducing calorific intake is much easier to sustain because of the fact that five days out of seven are unrestricted.

Could it be that eating hardly anything twice a week is doable because of the fact that, for the rest of the time, one is at liberty to enjoy whatever one fancies, be it cake, steak, or booze? However hungry you might get on the fast day, is the knowledge that you could have a full English breakfast the next day enough to get you through?

It seems to me that this particular approach to eating might not only be easier to stick to than others, but could also encourage deeper consideration of one’s relationship with food. Having not tried this diet myself, I can’t comment from first-hand experience, but I suspect that on fast days, you are more acutely aware of your body’s need for food than on days when you’re eating whatever you want. By deliberately depriving yourself of the ‘usual’ amount of food, you are choosing to make yourself somewhat uncomfortable which much have psychological and maybe spiritual effects as well as physical ones.

The Islamic month of Ramadan uses fasting as a way of teaching Muslims self-discipline, self-restraint and generosity, as well as encouraging reflection on the suffering of the poor, who may be forced to fast through poverty. Being hungry is used as a vehicle for nurturing the skills needed to maintain self-control – acting as a tool for sustaining mindfulness. Perhaps some of these benefits can be gained through regular intermittent fasting as well.

Advocates of the 5:2 diet talk about quite enjoying the feeling of hunger (knowing that it will be short-lived) and of feeling exhilarated on the fast days and liberated on the days when no restrictions are in place. From the various accounts I’ve read of doing the diet, I have not seen explicit mention of spiritual or psychological benefits, but I have a suspicion that impacts on these domains may go some way towards explaining its popularity.

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